Sourdough and Sage Stuffing
Heat oven to 300° F. Spread the bread in a single layer on 2 rimmed baking sheets. Bake, tossing once, until dry, 30 to 40 minutes; transfer to a large bowl. Increase oven temperature to 375° F.
Meanwhile, melt the butter in a large skillet over medium heat. Add the celery, onions, 11/2 teaspoons salt, and 1/2 teaspoon pepper. Cook, stirring occasionally, until the vegetables are tender, 10 to 12 minutes. Stir in the sage. Transfer to the bowl with the bread. Add 1 set of mix-ins (Bacon, Pecan and Thyme or Pine Nut, Raisin, and Parsley), if desired.
Combine 2 1/2 cups of the broth and the eggs in a medium bowl. Add to the bowl with the bread and vegetables. Let sit, tossing occasionally, until the liquid is absorbed, 5 to 10 minutes. (Add up to 1/2 cup more broth if needed; the stuffing should feel moist but not have any standing liquid in the bottom of the bowl.)